Pacer Target Lap Time On SSD [Done 5.20]

As per http://pclapcounter.winnerbb.net/t1031-pace-cars-slowing-down , add ability to run pace cars to a target lap time rather than a set speed for Scalextric Sport Digital (C7042). SSDC has this feature and makes any variance in the speed of cars a non-issue because they will race to specific lap time.

Should be implemented per car rather than per driver to account for different lap times that the cars run best on the track to.